1. Field of the Invention
The present invention relates to instruments used for orthopaedic surgical procedures, and, more particularly, to an instrument for sizing holes made in bones for receiving implants and for pressurizing bone cement used for securing the implants in the holes.
2. Description of the Related Art
Total shoulder arthroplasty is a complicated orthopaedic procedure involving replacement of the humeral and glenoid components of the joint. Replacement of the glenoid component remains one of the more difficult aspects of the procedure. The glenoid labram is excised and the surface debrided of cartilage and soft tissue remnants. The prosthetic implant includes anchoring components inserted into holes prepared in the remaining bone of the scapula. Bone cement is used to affix the implant anchors in place in the prepared anchor holes.
While the shoulder does not frequently support the full weight of a persons body, and, therefore, may not be thought of as a heavy load bearing joint, the force exerted on the shoulder joint through normal use of the arm can be quite high. Stability of the joint, after total shoulder arthroplasty, relies on many factors, including the proper attachment of the glenoid prosthesis at the anchor site. Unstable attachment of the glenoid prosthesis can lead to later joint function difficulties. Bone cements have been developed to improve bonding between the bone and the anchoring components of the prosthesis. The implants themselves have been improved in design, with ridges or grooves on the anchoring components, to enhance bonding and adherence between the bone cement and the implant.
For a proper bond, a proper hole size must be formed. The anchors of the implant are inserted into holes in the bone, and must fit properly for the strongest bond. Known glenoid prosthesis anchoring components include a plurality of pegs or a keel, inserted into prepared holes in the bone. Holes for the anchoring components are prepared by drilling into the bone, using a template as a guide for proper location of the holes. Proper width and depth, or shape of the hole or holes requires proper tool selection and use.
Bone cement delivery guns have been utilized to promote the effectiveness of implant fixation by improving penetration of the bone cement into the cancellous bone. Ratchet operated guns delivering a consistent flow of bone cement through properly sized and fitted nozzles are known.
What is needed is an orthopaedic instrument which is simple and easy to use, to pressurize bone cement in a prepared hole for the anchors of an implant, improving penetration of the bone cement into the surrounding cancellous bone.
What is further needed is an orthopaedic instrument suitable for proper sizing of holes to receive orthopaedic implants.
The present invention provides an orthopaedic instrument and a method for using the instrument, to verify that a proper anchor hole has been created, and to pressurize bone cement in the prepared holes, forcing bone cement into the surrounding cancellous bone.
The present invention comprises, in one form thereof, an orthopaedic instrument having a shaft, a pressure plate on one end of the shaft, a bone facing surface on the pressure plate, and an implant anchor site probe extending outwardly from the bone facing surface of the pressure plate. A removable seal may be placed around the anchor site probe, against the pressure plate.
The invention comprises, in another form thereof, an orthopaedic bone cement pressurizer having a shaft with a first end and a second end. A pressure plate is disposed on the first end of the shaft, and includes a bone side surface. An implant anchor site probe extends outwardly from the bone side surface of the pressure plate. A seal is disposed against the bone side surface of the pressure plate, and forms a seal surrounding the implant anchor site probe.
The invention comprises, in yet another form thereof, an orthopaedic procedure for inserting an implant, comprising preparing a bone site to receive a prosthetic implant, including forming one or more implant anchor component receiving holes at the prepared bone site, depositing bone cement in the receiving holes; providing an instrument having an implant anchor site probe shaped similarly to implant anchor components of the prosthetic implant to be used; forcing the implant anchor site probe into the receiving holes; removing the implant anchor site probe; and implanting the prosthesis.
An advantage of the present invention is providing an orthopaedic instrument, which will consistently and uniformly pressurize bone cement in a hole prepared to receive an implant.
Another advantage of the present invention is providing an instrument and method for consistently and uniformly impregnating cancellous bone with bone cement for attaching a prosthesis.
Yet another advantage of the present invention is providing a surgical procedure for gauging proper size of a prosthetic implant site and pressurizing bone cement in the site.
A still further feature of the present invention is providing an orthopaedic bone cement pressurizing instrument which is easy to use and not prone to failure.